Postnatal dexamethasone exposure compromises childhood lung function in preemies
In very premature infants, postnatal exposure to dexamethasone while in the neonatal unit appears to reduce mean lung function at school age, according to a recent study.
Researchers conducted a follow-up study on 179 children who had entered into a randomized trial of two neonatal ventilation methods. Lung function outcomes included forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), forced vital capacity (FVC) and forced expiratory flow at 75 percent (FEF75), 50 percent (FEF50), 25 percent (FEF25) and 25–75 percent (FEF25–75) of the vital capacity.
At least one course of dexamethasone was reported in 28 percent (n=50) of participants, while the remaining had no exposure.
Adjusted multiple regression analysis showed that there were significant differences in favour of the unexposed children in terms of FEF75 (difference, –0.53; 95 percent CI, –0.85 to –0.21; p=0.002), FEF50 (difference, –0.74; –1.05 to –0.43; p<0.001), FEF25 (difference, –0.75; –1.07 to –0.44; p<0.001) and FEF25–75 (difference, –0.70; –1.08 to –0.33; p<0.001).
The same was true for FEV1 (difference, –0.87; –1.24 to –0.51; p<0.001), FVC (difference, –0.38; –0.75 to –0.01; p=0.043), PEF (difference, –10.74; –16.06 to –5.41; p<0.001) and FEV1:FVC (difference, –1.43; –2.09 to –0.78; p<0.001).
The effect of dexamethasone exposure on lung function was confirmed when analysis was based on equivalent percentage of children with abnormal function. For instance, 21 percent vs 43 percent of the nonexposed vs dexamethasone-exposed children had abnormal FEF75 z scores, respectively.
Similar findings were reported for FEF50 (22 percent vs 57 percent), FEF25 (15 percent vs 47 percent), FEV1 (13 percent vs 42 percent) and FVC (8 percent vs 15 percent) z scores.